Two series of serum samples from Parsis and Iranis in Bombay have been typed for haptoglobin and transferrin groups: smaller numbers were typed for caeruloplasmin, protease inhibitor and albumins. In addition serum alkaline phosphatase types and the presence of C 5 esterase was determined for the first series of Parsi samples. The Hp1 gene frequency was significantly different for the Parsis and Iranis (0.14 and 0.22, respectively). Three transferrin B2 variants were found in 612 Parsi but none in 109 Irani sera. Two types of caeruloplasmin variants were present, CpA and CpCNew Haven and the CpA gene had a frequency of 0.02. No albumin or protease inhibitor variants were detected. Similarly, no C5+ serum esterase phenotypes were detected, but 39% of male and 15% of female sera were of type 2 (AB) for the alkaline phosphatase system. The lower frequency in females is related to their pregnancy status: there were marked differences also in the frequency of type 2 in relation to the ABO blood groups.